Rotary dust separator



N A V L Vl S G.

ROTARY DUST SEPARATOR Filed Aug. 23, 1953 2 Sheets-Sheet 2 n [N1/EN TOR.

SHQ @son SUM/ar' 1 gli ,um l" l Y ATTORNEY Patented Apr. 28, 1936 UNITED STATES PATENT OFFICE American Air Filter Company, Inc.,

Louisville,

Ky., a corporation of Delaware Application August 23, 1933, Serial No. 686,346

9 Claims. (Cl. 183-7'7) 'I'his invention relates to rotary dust separators of the type having an air or gas passage extending from an axial inlet outwardly to or along a peripheral dust chamber and thence passing either laterally or inwardly to an outlet opening or passage. separators of this type operate by rotation to whirl the gas passing therethrough and thereby utilize the centrifugal or dynamical forces of the whirl to force particles into the dust chamber Where they may be retained or directed into a dust hopper.

rll'he principal objects of this invention are to secure better gas flow conditions inthe gas passage, to facilitate the iiow of particles into the dust chamber and reduce the possibility of such particles reentering the gas passage, and, Where a dust hopper is used, to secure a more edective deposit of particles in the hopper.

Another object is to utilize the centrifugal force of the inward whirl in constructions where the gas, after whirling outwardly, is caused to whirl inwardly to secure an additional separation of dust and then transform the energy of the whirl for useful purposes.

The invention is illustrated in the accompanying drawings, wherein:

Figure l is a central vertical sectional view of one embodiment of my invention;

Figure 2 is a view showing the structure with the casing on the inlet side and the lower half of the impeller removed;

Figure 3 is a central vertical sectional view of an alternative form of impeller showing the uppermost and lowermost blades only, forthe sake of clearness; and

Figure 4 is an end elevation of the outlet side of the same impeller.

As illustrated, the invention is embodied in a separator having a casing i and an impeller t located within the casing. The impeller 2 cooperates with the casing i to dene a main gas passage which extends annularly outward from an axial inlet opening 3 to the end or periphery of the impeller, this end section of the main gas passage being hereinafter designated the peripheral section. The peripheral section of the gas passage communicates, radially outward through an endless annular opening or slot t in the casing, with an annular dust chamber or ring 5. In connection with the slot 4, it should be observed that its width is substantially smaller than the width of the peripheral section of the main gas passage.

The impeller 2 is mounted on a rotatable axis t and provided with blades 1 which extend transversely across the inlet passage and longitudinally along the passage, preferably from the inlet opening to the periphery. Insofar as it is possible, these blades are preferably arranged in the manner described and illustrated in my copending application filed October 2, 1930, and serially numbered 485,941, which issued as Patent No. 1,941,449, on January 2, 1934. The impeller is rotated in the direction shown by the arrow in any suitable manner, preferably through the agency of a motor connected to the axis 6. However, rotated, it is apparent that the blades 'i will rotate or centrifuge the gas as* it passes outwardly, and thus subject the contained particles to the action of centrifugal force, therebyforcing the particles outwardly to the periphery, where they pass through the slot t into the dust ring t. The extent to which the particles pass through the slot t and remain in the dust ring 5 depends somewhat upon the absence of turbulence in the gas passage. l have found that the securement of smooth flow conditions is enhanced by providing a passage which contains no abrupt change in area or direction of flow and whose ow area, from a point substantially in advance of the slot to the slot, remains substantially constant or is gradually decreased. While the controlled flow area should extend from the slot upstream approximately as far as the inner ends of the blades l, it need not necessarily extend beyond such ends but preferably is made to extend to a greater degree. Accordingly, the cooperating walls oi" the casing and impeller are curved and spaced to define a passage of the desired contour whose flow area from inlet to periphery is substantially equal to or less than the inlet flow area.

The particles which enter the dust ring will either rotate with the gas in the ring or be deposited upon the walls thereof. Whatever occurs, I have discovered that the separating efiiciency can be increased by augmenting the free rotation of the gas within the dust ring, that is to say, the rotationy due to the passing of whirl energy through the slot. This can be accomplished by rotating the entire structure, casing and all. Such method, however, either prevents the continuous operation of the device or necessitates special apparatus for effecting the removal of the dust contained in the dust ring during the operation. Where continuous operation is desired, good results can be obtained by providing the dust ring with fan blades and connecting the blades so that they rotate with the impeller 2. This can be accomplished conveniently by extending the blades 1 through the slot 4 into ring 5 as indicated at 8. Manifestly, as the blades I rotate, the air in the dust ring is positively driven instead of being rotated simply because of the whirl energy passing through the slot.

In order to remove the dust from the dust ring during the operation of the machine, a hopper 9 is provided at the bottom of the ring. The hopper 8 may be connected to the dust ring by a single passage. more effective separation however, can be obta ned by dividing such passage to provide inlet and outlet channels of communication between the hopper and ring. Accordingly, the construction illustrated contains a member I0 which cooperates with the casing I to define an inlet channel II-having an inlet orifice pro- Jecting partially across the dust ring and positioned to face up-stream so as to receive the dust and air sweeping along the periphery of the dust ring 5, and direct them into the hopper, and an outlet channel I2 having an outlet orifice positioned to discharge air coming from the hopper into the dust ring, the direction of discharge preferably being in the direction of rotation. 'I'he inlet channel II terminates in a spout I 3 which is bent to direct the incoming flow of air and dust away from the hopper orifice of the outlet channel I2. Furthermore, the hopper is made wide to provide a large settling area and thereby facilitate the settling of dust in the hopper. This not only permits a greater interval of time in which the dust may be settled, but also lessens the concentration of dust in the gas, whereby the loss cf dust due to leakage is minimized. 'I'he hopper 9 is provided with a suitable closure which permits the removal of the dust during the operation of the machine.

The main flow of air after passing the slot 4, may be discharged from the gas passage in any suitable manner. Where its discharge at this point is desired, the arrangement of parts shown in the copending case previously mentioned may be used to advantage. It may be pointed out that in that arrangement, a scroll outlet passage is utilized to transform the energy of the whirl into pressure. In order to secure this useful transformation and also produce an additional separation of dust, I make the gas passage extend inwardly to an axial outlet opening and divide the passage into an outer unrestricted annular portion and an inner restricted annular portion. The unrestricted annular portion designated I4 preferably extends from the periphery inwardly for a suitable distance, the blades 1 being, therefore, terminated at the plane of the slot. The air is thus permitted to whirl or vortex inwardly in the unrestricted portion with a resulting marked increase in its velocity. As its velocity increases, its centrifugal force will also increase, consequently tending to throw all of the escaping particles outwardly with the result that some of them are recaptured. If this whirling stream were permitted to pass on to the outlet passage. the energy of the stream would be dissipated by swirls and eddys. Hence, to avoid this loss, the restricted portion of the gas passage is provided with blades l5 which are secured to the adjacent wall of the casing I. These blades, at their inlet ends, are arranged to conform with the direction of travel of the gas and are smoothly curved toward their outlet ends to produce a radially inward discharge. In this manner, the swirl energy is transformed from velocity to pressure.

If desired, the swirl energy in the restricted portion may be transformed into driving energy. The alternative arrangement shown in Figures 3 and 4 discloses such type of structure. Here the blades are secured to the impeller 2. Now,

when the high velocity gas strikes the slower moving blades of the impeller 2, the energy of the gas will be consumed in driving these blades and thus reduce the energy otherwise required to operate the machine. Naturally, this will decrease the velocity of the gas without producing a corresponding change In its pressure. The curvature of the blades I5 in this type of structure is, of course, made somewhat different from that of the stationery blade type to conform to the relative changes in inlet and discharge direction of the gas.

Having described my invention, I claim:

1. A rotary dust separator of the class described having an axis of rotation and an axial inlet, comprising means for centrifuging gas about' said axis, means defining a passage for the fiow of said centrifuged gas from said inlet outwardly, and an outwardly located annular dust ring communicating with the outer portion of said passage through an annular slot, said passage having between the slot and a point substantially in advance of it a flow area which does not increase in the direction of flow.

2. A rotary dust separator of the class described having an axis of rotation and an axial inlet, comprising means for centrifuging gas about said axis, means defining a passage for the flow of said centrifuged gas from the said inlet outwardly, an outwardly located annular dust ring communicating with the outer portion i of said passage through an annular slot, said slot having a Width substantially smaller than the width of the adjacent portion of said passage, and means for augmenting the free rotation of gas in said ring.

3. A rotary dust separator of the class described having an axis of rotation and an axial inlet, comprising means for centrifuging gas about said axis, means defining a passage for the flow of said centrifuged gas from said inlet outwardly, an outwardly located annular dust ring communicating with the outer portion of said passage through an annular slot, the width of said slot being substantially smaller than the width of the adjacent portion of said passage, and a series of blades in said dust ring for positively rotating the gas therein. I

4. A rotary dust separator of the class described having an axis of rotation, comprising means for centrifuglng gas about the said axis, means defining a passage for the outward flow of said centrifuged gas, an annular dust ring communicating with the periphery of said passage through an annular slot, the width of said slot being substantially smaller than the width of the adjacent portion of said passage, and blades passing through said slot into said dust ring for positively rotating gas therein.

5. A rotary dust separator of the class described having an axis of rotation, comprising means for centrifuging gas about said axis, means defining a passage for the outward flow of said centrifuged gas, means defining an annular slot communicating with the outer portion of said passage and affording an outlet through which air and particles may be discharged from said passage, the width of the slot being substantially smaller than the width of said passage adjacent the slot, and blades within the slot for positively rotating the air passing therethrough.

6. A rotary dust separator of the class described having an axis of rotation, means defining an annular slot extending around and spaced outwardly from said axis, means for centrifuging dust-laden air outwardly through said slot, and an endlessl dust ring extending around said axis and communicating with the outlet of said slot, said ring providing an endless path for the flow of air and dust about said axis, in combination with a dust hopper, and means defining inlet and outlet channels of communication between said ring and hopper, said inlet channel having an inlet orifice projecting partially across the dust ring and positioned to face up-stream so as to receive dust and air sweeping along the periphery of the ring and direct them into the hopper and said outlet channel having an outlet orice positioned to discharge air coming from the hopper into the dust ring.

7. A rotary dust separator of the class described having an axis of rotation, means dening an annular slot extending around and spaced outwardly from said axis, means for centrifuging dust-laden air outwardly through said slot, and an endless dust ring extending around said axis and communicating with the outlet of said slot, said ring providing an endless path for the flow of air and dust about said axis, in combination with a dust hopper, and means dening inlet and outlet channels of communication between said ring and hopper, said inlet channel having an inlet orice projecting partially across the dust ring and positioned to face up-stream so as to receive dust and air sweeping along the periphery of the ring and direct them into the hopper and saidfoutlet channel having an outlet orice positioned to discharge air coming from the hopper into the dust ring, and means for positively rotating the air in said dust ring.

8. A rotary dust separator of the class de1 scribed, having an axis of rotation and an annular gas passage extending around said axis and having a peripheral section spaced outwardly therefrom, said separator comprising means for centrifuging the gas so as to pass it rotationally through said section, means defining a gas passage for the inward now of gas from said section, said inward passage having an outer unrestricted annular portion in which the gas whirls as it passes and an inner annular portion, and restricting means in said latter portion for transforming the energy of the whirling stream.

9. A rotary dust separator of the class described, having an axis of rotation and a gas passage at its periphery, comprising means for causing the gas to rotate in said passaage, means dening a gas passage for the inward flow of gas from the periphery to the axis, said inward passage having an outer unrestricted annular portion in which the gas whirls as it passes and an inner restricted portion, and a series of blades arranged in said restricted portion to transform the energy of the whirl, the inlet ends of said blades being arranged to conform with the direction of travel of said whirling gas and being curved toward their outlet ends to produce a radially inward discharge.

STIG GZSON SYLVAN. 

